Pneumatic blow-out for electric switches.



E. H. DEWSON.

PNEUMATIC BLOW-OUT FOR ELECTRIC SWITCHES.

APPLICATION FILED 00113, 1905.

1,039,264. Patented Sept. 24, 1912.

UNITED STATES PATENT OFFICE.

EDWARD H. IJE'WSQN,v OF NEW roan, N. Y., Assicmo'n r 'rnn wns'rmenoosn TEENNSYLVANIA.

PNEUMATIC BLOW-OUT FOR ELECTRIC SWITCHES.

Specification of Letters Patent. Patented Sept. 24, 1912.

Application and October s was Serial No. 252,553.

To all whom it may concern a citizen of the United States, residingI in New York city, county and State of ew York, have invented a certain new and useful Improvement in Pneumatic Blow-Outs for Electric Switches, of which the following is a specification.

' This invention relates to pressure operated electric switches, and has for its object to provide an improved pneumatic blow-out device adapted to are at the time 0 throwing the switch to open the circuit.

According to my improvement, the piston to which fluid under pressure is admitted for throwing the switch operates in a closed chamber, so that in moving .out it compresses the air in the chamber on its outer side.-

From .this chamber or space ducts or pas sages lead into close contact points and discharge across the same, whereby the stream or jet across the are at the time the switch is opened and thereby prevents in-:

jurious burning of the contact points,

While my invention, broadly considered, is adapted for use in connection with electric switches generally, it is especially applicable to the switch of an electric pump governor, inwhich a piston is employed for positively and quickly throwing the switch the circuit and stop the motor driven to open the pressure reaches a precompre'ssor when determined point.

In the accompanying drawing, Figure 1 1s a diagrammatic section showing my improvement applied to any pressure operated electric switch, and Fig. 2 a sectional view of an electric pump governor with my improved pneumatic blow-out applied thereto.

JAS shown in the drawing, the construction comprises an electric switch having a movable member or contact bar 3 connected with rod 6' of a piston" or movable lunger 5 which operates in a substantia ly closed chamber 2 and, upon'its outward stroke is discharge a jet of air across the contact points and extinguish the.

proximity to the switch air which is compressed by the, movement of the piston is directed in a h v adapted to compress the air in chamber 2. A Be it known that I, EDWARD H. Dawson,

duct or passage 8 leads from said chamber and has its outlet-so disposed as to discharge a jet or blast of air transversely across the line of the separating contact points 3 and 4 of the electric circuit as the switch is thrown to its open position. Although this air pamge 8 may be arranged in any desired manner, it is preferably formed in the piston rod 6 and at its outer end is provided with one or'more jet openings according to the number of stationary cont-act fingers 4 at which the circuit is opened. Any desired means may be employed for operating'the switch, such as a spring 7 normally tending to close the switch and a three-way cock 10 adapted to supply fluid under ressure to and release the same from the ace of the pistonthrough a pipe or passage 9. When it is desired to throw the switch to open the circuit, the cook 10 may be turned to admit pressure to the piston 5, thereby forcing the same outward to separate thecontact points of the switch and at the same time compressing the air in chamber 2 to such an extent as to cause a jet or jets of air to be discharged through the port or passage 8 directly across thefiline of the opening contact points. In this manner the arcs are effectually extinguished and all injurious burning out of the switch contact points prevented.

In Fig. 2 I have illustrated my invention applied to an electric pump overnor, in

which valve mechanism controlled by the pressure of the pump or reservoir connected to pipe 11 is employed for supplying and releasing fluid under pressure to and from the actuating piston ferred form of such valve mechanism may comprise a main valve 16 operating in chamber 12 by stem 13 and piston heads 14 and 15 working in chambers and 21. The regulating chamber communicates with the source of air pressure through port 19 and has a diaphragm 26, which is subject to the high pressure adjustable spring 27, the stem 28 operating the valve 29 for venting air from piston chamber, 20 through port 30 5 of the switch. A pre-l.

8 and across the line rises to the predetermined cutting out point. Air under pressure from the pump or reservoir may also be supplied through pipe 11 and passage 22 to another regulating chamber 24 having diaphragm 31 with stem 33 for operating the regulating valve 34, which vents the pressure from piston chamber 21 through port 23 to the atmosphere when the pump pressure diminishes below the cutting in point at which the low pressure spring 32 is adjusted. With the switch closed and the pump working as indicated in the drawing, the pressure rises in chamber 24 on diaphragm 31 and closes the regulating valve 34. The pressure also continues to increase in chamber 25 on diaphragm 26 until it reaches the desired cutting out point at which the spring 27 is adjusted, whereupon it opens the regulating valve 29 and releases the pressure from chamber 20 back of piston head 14, which, area than piston head 15, immediately travels to the left, carrying with it the valve 16 to open the port 9 leading to the switch actuating piston 5. Air under pressure then flows rapidly through port 9 to the face of piston 5 and forces the same out-ward with a strong quick movement, thereby compressing the air in chamber 2 on the opposite side and causing the air to discharge in a jet or blast through the outlet passage of the separating contact points 3 and 1 of the switch, thereby effectually extinguishing the arc. With the valve 16 in its left position the chamber 25 is open to the atmosphere through port 19, cavity 17 and exhaust port 18, so that the regulating valve 29 is closed and the pressure of the valve chamber 12 equalizes around the two piston heads into chambers 20 and 21. As the circuit is then open and the pump stopped, the pressure diminishes in chamber 24 until it reaches the cutting in point at which the spring 32 operates to open the regulating valve 34: and vents the pressure from piston chamber 21 to the atmosphere. T his causes the piston heads and valve 16 to move to the right to the position shown in the drawing, in which the port 9 is open to the atmosphere through cavity 17 and exhaust port 18, whereupon the pressure is released from the face of actuating piston 5 and the spring 7 returns the same to its inner position, thereby again closing the switch and starting thepump.

It is important that the actuating piston should move outward with a quick positive movement suflicientto compress the air in chamber 2 and produce a comparatively strong jet or blast across the contact points to extinguish the arcs. Any valve mechanism governed by the pump pressure and which operates to give a prompt and full opening of the supply port 9 may be employed for this purpose, and I lay no claim being of a larger to the specific form of valve mechanism shown, since the same is not my invention, but is covered by Patent N o. 87 9,699, issued February 18, 1908.

By means of my improvement all blowout magnets, or other devices which have heretofore been employed tor preventing injurious effects of arcing at the switch contact points may be dispensed with, thereby greatly reducing the cost of manufacture, while at the same time providing a simple inexpensive and efficient means for extinguishing the arcs and preserving the contact points.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is 1. A pressure operated electric switch mechanism comprising a movable switch member, a piston for operating the same, means for suddenl admitting fluid under pressure to said piston to cause the quick movement thereof, a chamber on the opposite side of said piston and a duct or passage leading from said chamber to the switch contact points, communication through said passage being controlled by the movement of the piston.

2. A pressure operated electric switch mechanism comprising a' movable switch member, a cylinder and piston for operating said switch, means for controlling the supply of fluid under pressure to and the release from the cylinder on one side of said actuating piston, and a duct or passage leading from the cylinder on the opposite side of said piston and directly controlled by said piston for discharging the air compressed by the movement of the piston upon the switch contact points.

3. A pressure operated electric switch mechanism, comprising a piston and rod carrying the movable switch member, a chamber on one side of said piston, and a passage leading from said chamber through the piston rod for directing an air jet upon the switch contact points.

4. A pressure operated electric switch mechanism comprising a movable switch member, a cylinder and piston for operating said switch, a pressure controlled valve device for supplying fluid to actuate said piston to open the circuit, and a duct or passage directly controlled by said piston and leading from the cylinder on the opposite side of the piston to a point near the switch contacts for discharging thereon the air compressed by the movement of the piston in opening the switch, communication through said duct being cut oil in the closed position of the switch.

5. An electric pump governor comprising a switch having a movable contact point, a piston for operating said switch to open the circuit, means subject to the pump pressure for controlling the action of said'piston and In testimony whereof I have hereunto set agaptgd to cause 2i quick positivehmovement my hand.

0 Sai piston, a (3 am er in Whic the air is compressed by the movement of the piston, EDWARD DEWSON' and a duct or passage for discharging a. Witnesses:

blast'of air from said chamber to the switch R. F. EMERY,

contact points when the circuit is opened. J. B. MACDONALD. 

